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Vol. 18 (2015 year), No. 2
Kaulina T. V., Bayanova T. B., Talat Ahmad, Lyalina L. M., Mishra M. K., Nitkina E. A., Elizarov D. V., Serov P. A.
Evolution of the Central Indian tectonic zone:Geochemical and isotope-geochronological data
In the framework of the Russian-Indian joint research projects geochemical and geochronological study of granitoid rocks across the Central Indian Tectonic Zone has been carried out. Geochronological data suggest that the Central Indian Tectonic Zone is composed primarily of Proterozoic rocks, formed as a result of several stages of granitoid magmatism: at 2.43, 2.34-2.31, 1.73-1.72 and 1.53-1.51 Ga. Metamorphic transformations reflected by Sm–Nd and Rb–Sr systems of rocks and minerals occurred 1.37-1.1 Ga ago that allows comparing the final processes in the Central Indian Tectonic Zone with the Grenville orogeny and it can be used for the reconstruction of Rodinia
(in Russian, стр.10, fig. 3, tables. 1, ref 13, Adobe PDF, Adobe PDF 0 Kb)
Vol. 21 (2018 year), No. 1, DOI: 10.21443/1560-9278-2018-21-1
Nitkina E. A., Bayanova T. B.
Isotope-geochronological study of Ingozero massive (the Kola Peninsula)
The Ingozero massive composed of Archeaen gneisses and granitoids is situated in the north-eastern part of the Belomorian mobile belt. The Ingozero massive petrochemical and geochemical characteristics are similar to those of tonalite-trondhjemite-granodiorite (TTG) complexes established on other Archean shields. High concentrations of Na, Ca, and low of K characterize the gneisses of the Ingozero massif and the samples points lie on the tonalite and trondhjemite fields on the Ab-An-Or diagram. The high content of light rare earth elements and the absence of Eu anomalies indicate the origin of rocks from enriched sources without the essential role of fractional crystallization. The isotope U-Pb single zircon grains dating of the biotite gneisses yielded the oldest age for the Ingozero gneisses magmatic protolith at 3 149 ± 46 Ma. Model Sm-Nd ages have shown the formation of the gneisses protolith initial melt occurred at 3.1–2.8 Ga. The ages of metamorphic processes were determined by isotope U-Pb dating (ID TIMS): biotite gneisses – 2 697 ± 9 Ma; amphibole-biotite gneisses – 2 725 ± 2 and 2667 ± 7 Ma; and biotite-amphibole gneisses – 2 727 ± 5 Ma. The ages for granitoids, which cut the deformed gneisses are 2 615 ± 8 Ma and 2 549 ± 30 Ma for plagiogranites and pegmatoid veins in gneisses respectively
(in Russian, стр.9, fig. 5, tables. 4, ref 21, adobe PDF, adobe PDF 0 Kb)
Vol. 23 (2020 year), No. 1, DOI: 10.21443/1560-9278-2020-23-1
Nitkina E. A., Kaulina T. V. , Kozlov N. E.
The ages and rock mineral composition of the Pechenga eastern frame, the Kola region
The research and dating of rocks in the area of the Central Kola block (the Kola Peninsula) is due to the need to develop the Lyceum uranium ore area, the most promising for uranium mining in the Kola region, located in close proximity to the study area and composed of similar gneisses from the Kola series. Within the Central Kola block, Archean complexes are represented by granite-gneisses and migmatites with relicts of biotite-plagioclase, biotite-amphibole-plagioclase gneisses, amphibolites, garnet-biotite-plagioclase and aluminous gneisses containing interlayers of ferruginous quartzite (quartz metasomatites) of various capacities. The rocks are repeatedly metamorphosed in conditions from high-temperature steps of the amphibolite facies to the granulite facies. Geological and geochronological methods have established the sequence of geological processes manifested in the rocks of the Kola series of the northwest framing of the Pechenga structure. The results of U-Pb dating are determined by zircon grains of the following genesis: metamorphic – in gneiss; magmatic and metamorphic – in metagabbro; metamorphic and metasomatic – in quartz metasomatite. The data obtained have made it possible to establish the age sequence of geological processes: 2.8 Ga – the time of metamorphism of garnet-biotite gneisses; 2,722 ? 9 Ma – crystallization of granodiorites; 2,636 ± 41 Ma – the formation of aplitic granites; 2,620 ? 16 Ma – the emplacement of pegmatites; the age of aplitic granites and pegmatites marks the final stages of the Archean evolution of the region; 2,587 ± 5 Ma – the emplacement of gabbroids, 2,522–2,503 Ma – the period of the thermal process associated with the formation of quartz metasomatites during the metamorphism of gabbro and garnet-biotite gneisses; 2,507 ± 7 Ma – metamorphism, schist and budding of gabbroids.
(in Russian, стр.10, fig. 4, tables. 1, ref 31, AdobePDF, AdobePDF 0 Kb)
Vol. 25 (2022 year), No. 1, DOI: 10.21443/1560-9278-2022-25-1
Nitkina E. A., Serov P. A.
Zircon morphology and isotope U-Pb and Sm-Nd dating the rocks of the Kanozero alkaline granite massif (the Kola region)
The U-Pb dating zircon and Sm-Nd dating the whole rock and secondary minerals from the Kanozero massif of alkaline granites of the Kola region (the Fennoscandian shield) have been carried out. The age of alkaline granites of the Kanozero massif by zircon is 2667 ± 36 Ma, aplite-like alkaline granites – 2301 ± 13 Ma and blastomylonites – 2264 ± 12 Ma. The crystallization temperature of zircon has been estimated from the crystal habit. According to the zircon morphology of alkaline granites and blastomylonites the conditions during the crystallization process of the Kanozero massif have been established as long-term cooling high-temperature volatile- and alkali-rich crustal-mantle melts. The mineral Sm-Nd isochron by whole rock and by secondary minerals – biotite and titanite – has an age of 1921 ± 53 Ma interpreted as the time of regional Svecofene metamorphism. Based on the obtained isotopic data it can be noted that the rocks of the Kanozero massif of alkaline granites have similar features of formation and transformation with alkaline granites of the Keivsky terrane.
(in Russian, стр.11, fig. 8, tables. 3, ref 24, AdobePDF, AdobePDF 0 Kb)